An orbiting rotary compressor has similarities to both a scroll compressor and a rotary compressor. The similarities to a scroll compressor include multiple compression chambers defined by a driven member which has orbiting motion relative to a fixed member to which it is engaged. The similarities to a rotary compressor include a compression chamber defined between the outer cylindrical surface of a roller or piston, the inner cylindrical surface of a compressor block about which the piston moves epicyclically, and a vane extending between these cylindrical surfaces.
In general, orbiting rotary compressors include a fixed compression member and a moving compression member engaged therewith. The fixed and moving compression members typically include planar bases and circumferentially-engaged cylindrical surfaces which extend perpendicularly from the bases. When the fixed and orbiting compression members are assembled relative to one another, the cylindrical surfaces define a space therebetween which is a compression chamber. A single cylinder orbiting rotary compressor is one having a single pair of engaged fixed and orbiting compression member cylindrical surfaces, whereas a multiple cylinder orbiting rotary compressor is one having a plurality of pairs of engaged fixed and orbiting compression member cylindrical surfaces. In the latter case, the fixed compression member may be provided with an inner cylindrical surface and an outer cylindrical surface between which a portion of the orbiting compression member defined by concentric inner and outer cylindrical surfaces is located. In either case, compression chambers are defined by the cooperating fixed and orbiting compression member surfaces and a vane extending therebetween.
An example of a twin compression chamber rotary type compressor is disclosed by U.S. Pat. No. 5,399,076 to Matsuda et al. With reference to its drawings, a fixed compression member includes a base from which a cylindrical post perpendicularly extends to define a fixed inner cylindrical surface. A moving compression member or rolling piston having an extending portion defined by concentric cylindrical surfaces is positioned with its inner cylindrical surface disposed about the post to define, with a first reciprocating vane, a first, inner compression chamber. The fixed and moving compression members are encased by a housing which has a cylindrical surface surrounding the extending portion of the moving compression member to define, with a second reciprocating vane, a second, outer compression chamber. Each compression chamber is provided with a suction or inlet port and a discharge or outlet port, each discharge port being provided with a check valve to prevent reentry of compressed refrigerant into the compression chamber.
The first reciprocating vane is mounted in a slot provided in the post and the second reciprocating vane is mounted in a slot provided in the housing, to respectively divide the inner and outer compression chambers into sub-chambers when the respective vane is not completely disposed within its slot. The first and second vanes are arranged relative to one another such that the timing of the commencement of the compression processes in the inner and outer compression chambers are 180 degrees out of phase.
With reference to FIG. 5(a) of Matsuda et al. ""076, when the moving compression member cylindrical portion has a position of zero degrees, the first vane is fully extended from its slot and the inner compression chamber is midway through the compression process, with compressed refrigerant being discharged from one compression sub-chamber and suction pressure gas being drawn into the second compression sub-chamber. Here, the outer compression chamber is filled with gas substantially at suction pressure and ready be compressed; the second vane of the outer compression chamber is fully depressed into its slot, and the moving compression member cylindrical portion covers both the suction and discharge ports of the outer compression chamber. By covering the ports of the outer compression chamber at the commencement of the compression process, leakage of refrigerant from the outer compression chamber is prevented.
As the moving compression member cylindrical portion moves to a position of 180 degrees (FIG. 5(c)), the outer compression chamber is midway through the compression process. Here, one of its sub-chambers contains compressed refrigerant which is being discharged through the discharge port, and its other sub-chamber is being filled with suction pressure gas through the suction port. The first vane of the inner compression chamber is now depressed into the slot in the fixed compression member post. The inner compression chamber is now filled with suction pressure gas and its compression process begins. In this position, the orbiting compression member cylindrical portion covers the inlet and outlet ports of the inner compression chamber to prevent fluid leakage.
A potential problem with some previous rotary compressors is that sliding engagement of the moving compression member relative to tip of the vane may wear the vane tip and/or place undesirable shear or bending stresses on the vane. Thus, it may be desirable to prevent rotation of the moving compression member.
Some previous rotary compressors limit rotation of the moving compression member in a manner similar to that used to prevent rotation of the orbiting scroll member in scroll compressors. Previous orbiting rotary compressors may utilize an Oldham coupling between the planar base of the moving or orbiting compression member and the main bearing of the compressor, which is disposed between the compression mechanism and the electric motor within the hermetic shell. Examples of such orbiting rotary compressors are disclosed in U.S. Pat. Nos. 5,302,095 and 5,383,773 to Richardson, Jr. Accommodating the Oldham coupling between the main bearing and Oldham coupling in previous orbiting rotary compressors has resulted in the fixed compression member and main bearing being separate components which must be assembled together, which may be undesirable.
Additionally, some other previous orbiting rotary compressors have relied on an outboard bearing or a fixed compression mechanism plate member located on the axial side of the compression chamber opposite the fixed compression member to define and seal the compression chamber, an axial end of the orbiting compression member in sliding abutting engagement with the interfacing planar surface of this bearing or plate member. U.S. Pat. No. 6,152,714 to Mitsuya et al. discloses an example of such a compressor. Reducing the number of separate components which define the sealed compression chamber(s) is desirable, as would be an orbiting rotary compressor having an orbiting compression member with an base integral with that member""s cylindrical surface(s).
Moreover, previous orbiting rotary compressors often rely on springs to bias the vane(s) against the moving compression member. Assembly of the compressor is often complicated by including parts such as these small springs. It may be desirable to exclude them where possible to simplify assembly.
The present invention addresses several of the above-identified shortcomings of previous orbiting rotary compressors, and provides advantages associated with each of the above-identified desirable features.
Generally, the present invention includes compressor embodiments having a fixed compression member having integral, compression chamber-defining cylindrical surface(s), and which also provides a main bearing, and an orbiting member which is provided with integral base and compression chamber-defining cylindrical surface(s). Such a compressor may have a single compression chamber advantageously having a vane which does not require a spring to bias it into sealing engagement with the orbiting compression member, or a compressor having plurality of compression chambers, each having a vane, wherein at least one vane also advantageously does not require a biasing spring. An Oldham coupling for such a compressor may be either engaged with the orbiting and fixed compression members, or with the orbiting compression member and an outboard bearing.
Certain embodiments of the present invention provide an orbiting rotary compressor assembly having a compression mechanism disposed in a housing and including relatively moving fixed and orbiting compression members including extending portions having surfaces engaged with each other and between which a compression chamber is located. The orbiting member has a centrally-located hub which moves eccentrically relative to the axis of rotation of a drive shaft in driving engagement with the hub. A vane operatively engages the fixed member extending portion and the orbiting member extending portion, and partially defines the compression chamber. An Oldham coupling is disposed about and is in engagement with the hub, and is in engagement with the fixed compression member, rotation of the orbiting compression member being prevented by the Oldham coupling.
Certain embodiments of the present invention provide an orbiting rotary compressor assembly in which a compression mechanism is disposed in a housing and includes relatively moving fixed and orbiting compression members, and an outboard bearing which is fixed to the fixed compression member and supports the orbiting compression member. The compression members each have a base from which an extending portion extends, these extending portions having surfaces engaged with each other and between which a compression chamber is located. The orbiting member further has a centrally-located hub extending from its base. A rotating drive shaft having an axis of rotation is in driving engagement with the orbiting compression member hub, and the hub has eccentric movement relative to the axis of rotation. A vane operatively engages the fixed and orbiting member extending portions and partially defines the compression chamber. The hub and the fixed compression member form a first pair of relatively moving elements, and the outboard bearing and the orbiting compression member base are a second pair of relatively moving elements. An Oldham coupling is reciprocatively engaged with each relatively moving element of one of the first and second pairs of relatively moving elements, rotation of the orbiting compression member being prevented by the Oldham coupling.